Preheat oven to 350F and line a baking sheet with parchment paper.
Add the butter and brown sugar in the bowl of a stand mixer and blend for a couple of minutes until they are creamed together.
Add the eggs, molasses, and vanilla and continue to mix until everything is combined.
Then add the spices, salt, baking powder, baking soda and mix well. Slowly add the flour until the dough forms.
Transfer dough to a flat surface sprinkled with flour. Divide the mixture into 2 equal pieces and form into 2 logs and flatten to about 1 inch height. Place on baking sheet and sprinkle with the icing sugar. Bake for 20-25 minutes. Remove from oven and let cool for about 10 minutes.
Place the logs on a cutting board. Using a serrated knife, cut the logs into 3/4 inch slices on a diagonal. Arrange back on the cookie tray and bake for 15 more minutes. Transfer to a cooling rack and let cool completely.